Leviticus 17:3
What man soever there be of the house of Israel, that killeth an ox, or lamb, or goat, in the camp, or that killeth it out of the camp, What man soever there be of the house of Israel, that killeth an ox, or lamb, or goat, in the camp, or that killeth it out of the camp,
God gave a positive command binding on all Israel that no sacrifice was to be offered except at the door of the tabernacle. The tabernacle at Shiloh was the one appointed place of sacrifice and worship for the whole nation. To erect another altar for sacrifice elsewhere was rebellion against the Lord and departure from God. Such disobedience, when committed by a large company, brought the wrath of God upon the whole nation, not upon the offenders alone.
Therefore the tribes settled east of Jordan were required to live without a local altar for sacrifice. If they were unwilling to abide in their land without that privilege, the right course was to leave their land rather than transgress. They were invited instead to come over and share the possessions and privileges of their brethren on the west, where they could remain obedient by worshiping at the one altar.